It should be an atomic replace - create a new table, do your inserts, swap the new table in. This way you aren’t left without the data during the rebuild, and you are guaranteed a consistent state since DDL is transactional in PostgreSQL.

Make the new table unlogged while it’s being populated as well for that performance improvement if you want, since the atomic replace guarantees your consistency anyway.

Alternative if it’s not a full rebuild, move from a delete/insert to using INSERT .. ON CONFLICT DO UPDATE where possible. I do this for cache tables that store materialized summary views that are updated by pgAgent jobs.

If you are deleting “old” data out then maybe use partitioned tables so you can just DROP the table containing the data you want gone.